1. Field of the Invention
The present invention is generally related to a carbon nanotube-polymer hybrid and the nanocomposite thereof, and more particularly to a chemically bonded carbon nanotube-polymer hybrid and the nanocomposite thereof.
2. Description of the Prior Art
Carbon nanotubes (CNTs) have shown attractive properties, such as light-weight, high strength, high toughness, high specific surface area, high thermal conductivity, that make them potentially useful in many applications. However, CNTs require organic functionalization to increase their solubility in organic solvents, compatibility with organic polymers, and processibility. The functionalization of CNTs with polymers has received much research attention because the products show the combined properties of CNTs and polymers. Most of the approaches require the pre-modification of CNTs to introduce functional groups to CNT surfaces, making the CNTs capable of reacting to the reactive groups of polymer chains. On the other hand, the preparation of CNT-polymer hybrids can use pristine (unmodified) CNTs. Polymers possessing functional groups that are reactive toward CNTs are suitable materials for functionalization of CNTs through this method.
The polymers capable of being covalently incorporated to CNTs are limited to two categories. The first category is polymers possessing functional groups that are reactive toward CNTs and the second category is polymers obtained with in situ polymerization. For example, the polymers possessing functional groups that are reactive toward CNTs can be polyamide having maleimide groups that react to CNTs through Diels-Alder reaction. But, the disadvantage of using the first category of polymers is that a specific method for reacting to CNTs is required for each different polymer. In addition, another disadvantage is that polymers have to possess functional groups that are reactive toward CNTs.
Polymer-functionalized CNTs, compared to the unmodified ones, usually show relatively good solubility in organic solvents and high compatibility to polymer matrix in CNT/polymer composites. However, the organic portions of functionalized CNTs are considered to be “impurities” that induce microscopic separation in the CNT/polymer composites and harm their properties. Therefore, the preferred method is to use polymers that are structurally close to the matrix polymers in CNT functionalization to decrease the “impurity” effect.
On the other hand, there is no reported method to have stable and non-reactive polymers, particularly like commercially available polymers and high performance engineering plastics, covalently bonded to pristine CNTs. That is, currently there is no general approach to functionalize CNTs to have CNTs and various matrix polymers covalently bonded.
The applications of CNTs to the modification of polymers demonstrate the improvements in the mechanical properties and conductivity of the polymers as well as the increase in their proton conductivity for a proton conductive membrane.